renamed references to "serveAssets" to "serveFiles"

[rokaicker]

🔗 Linked issue

Issue #180

❓ Type of change

• [x] 🐞 Bug fix (a non-breaking change that fixes an issue)
• [ ] 👌 Enhancement (improving an existing functionality like performance)
• [ ] ✨ New feature (a non-breaking change that adds functionality)
• [ ] ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Hi, I've corrected all lines that referenced "serveAssets" to "serveFiles".

Resolves #180

📝 Checklist

• [x] I have linked an issue or discussion.
• [x] I have updated the documentation accordingly.

Updated content/guides/digging-deeper/drive.md

[rokaicker]

Hi, I found that this issue was still open, and decided to quickly fix it up. Please let me know if any changes are required (I'm still new to open source in general).

If possible, would it be okay to accept this under the hacktober-accepted tag?

Thanks!

[thetutlage]

Thanks a lot for the PR :)